More police officers have been charged in civilian killings in 2015 than at any time in the last decade

After prosecutors in Ohio announced no criminal charges for the officers involved in 12-year-old Tamir Rice’s killing, the conversation now turns to what many have described as a miscarriage of justice in the matter.

For it’s part, the US Justice Department has said it will continue its investigation of Rice’s killing. In a statement issued Monday, the DOJ said it would “assess all available materials and determine what actions are appropriate.”

Though police officers are rarely charged when they kill a civilian, the trend has changed dramatically this year. At least 18 police officers have been charged with a crime in 2015 stemming from fatal encounters with people while on duty.

That’s a record that stretches back at least 10 years, according to research compiled by Bowling Green State University criminal justice professor, Philip Stinson — an ex-cop whose data was cited by the Wall Street Journal in September.

There was an average of about five prosecutions of law enforcement officers each year over the last decade.

There’s little doubt about what may have contributed to this year’s increase. Police killings have lately been the subject of intense media and political scrutiny.

Civil rights groups have pointed to one specific trend in these deaths — that they often involve unarmed people of colour.

Protests following police-involved deaths in Ferguson, Mo., New York, Baltimore, Chicago, South Carolina, and Texas have also cracked the veneer of unimpeachable innocence often afforded by the police badge.

But more court trials do not necessarily lead to more convictions. Retired San Francisco Bay area district attorney Tom Orloff explained it this way in The Wall Street Journal: “most jurors have the idea the cops are out to do the best job they can.”

Put another way, the prevailing notion in these matters is often the same; if the police use deadly force while performing their duties, it was probably necessary.

Minutes after shooting Rice, Officer Loehmann said that the 12-year-old — who had been holding an unmarked toy gun — gave Loehmann “no choice” as Rice “reached for the gun.” Loehmann shot Rice within two seconds of exiting his patrol car.

Screenshot/Laura Skelding/StatesmanBastrop County sheriff’s deputy Daniel Willis was accused of fatally shooting Yvette Smith in February, 2014 while responding to an emergency call. A mistrial was declared in September.

Despite the increased number of police officers tried in court for on-duty killings, “no single officer has been convicted of murder or manslaughter this year,” the WSJ reports.

Several high-profile police-involved deaths have been talked about of late, including the case of former Charleston, South Carolina police officer, Michael Slager, who has been denied bond as he waits for his murder trial to begin. Slager is accused of fatally shooting Walter Scott, an unarmed man who was running away from Slager during an encounter in April.

Five officers in Baltimore are facing separate trials over the death of Freddie Grey, a man who suffered a medical emergency that severed his spine 80% at his neck while he was in police custody. A mistrial was declared in the case of a sixth officer, William Porter, earlier this month.